Milling apparatus

ABSTRACT

In a milling machine there is a bowl in which there is a mixing member and a plurality of small milling elements such as beads or platelets and milling of a fluent material is achieved by driving the mixing member to cause relative movements of the milling elements. The heat generated by the milling process is removed from the bowl by a surrounding cooling jacket comprising spaced plates which define two cooling liquid chambers, the chambers being arranged so that cooling fluid flows down the first chamber in contact with the bowl, and then up the second chamber between the plates.

United States Patent 1 Morley 1 1 MILLING APPARATUS [75] Inventor: Douglas Morley, Halifax, England [73] Assignee: August's Limited, England [22] Filed: Apr. 1, 1974 [21] Appl. No.: 457,113

1,772,145 8/1930 Harter, Jr. 165/118 1 Aug. 5, 1975 Eppenbach 241/65 Laird l. 241/65 [5 7] ABSTRACT In a milling machine there is a bowl in which there is a mixing member and a plurality of small milling elements such as beads or platelets and milling of a fluent material is achieved by driving the mixing member to cause relative movements of the milling elements. The heat generated by the milling process is removed from the bowl by a surrounding cooling jacket comprising spaced plates which define two cooling liquid chamhers, the chambers being arranged so that cooling fluid flows down the first chamber in contact with the bowl, and then up the second chamber between the plates,

7 Claims, 3 Drawing Figures MILLING APPARATUS This invention relates to milling apparatus of the type comprising a bowl or container in which is located a rotatable mixing member; the bowl or container in use includes a plurality of milling elements such as small beads, blocks, plates or the like which may be of any suitable material such as glass, plastics material, which elements upon rotation of the mixing member perform by relative movements, the function of milling and dispersing into more finely divided form, fluent solid materials and dispersions placed in the bowl to be so milled. Such milling apparatus will be referred to hereinafter and in the appended claims as milling apparatus of the type aforesaid."

Milling apparatus of the type aforesaid has many uses in industry, such uses including for example the milling of a) paint pigments with solvent; b) pharmaceutical substances; c) printing inks; d) toothpastes; and e) flour.

As the milling proceeds on such a machine the temperature of the material in the bowl increases and consequently the temperature of the bowl increases. It is expedient to arrange therefore for some means whereby the heat generated by the milling process may be removed from the bowl and this invention is concerned with such a means.

According to the invention there is provided a milling machine of the type aforesaid wherein the bowl has an external cooling jacket into which water may be introduced to cool the bowl, said jacket being defined by a first plate extending around the bowl so as to provide a first cavity between the bowl and first plate, and a second plate extending around the first plate so as to provide a second cavity between the first and second plates, said first and second cavities being in communication at the lower ends thereof. and the top of the first cavity being open and the top of the second cavity being located so that cooling fluid introduced into the first cavity through the open top thereof flows down the first cavity then up the second cavity and then over and outwardly of the top edge of the second cavity.

Preferably, the said first and second plates extend around the whole periphery of the bowl.

The apparatus may further include a stationary water supply pipe located adjacent the top edge of the upper cavity and having holes therein from which water can issue in jets directed to the open top of the first cavity.

The top of the second cavity may define a restriction for the cooling fluid in orderto enable the build up of a head of fluid in the first cavity. The restriction may be defined by an apertured plate closing the top of the second cavity.

The bowl preferably is of circular sections and said first and second plates are curved to follow the bowl shape.

The milling apparatus may otherwise be identical with either embodiment of the invention illustrated and described in my US. Pat. No. 3,848,816.

An embodiment of the present invention will now be described by way of example, with reference to the accompanying drawing, wherein;

FIG. 1 is a side elevation of a milling apparatus according to the invention;

FIG. 2 is a sectional elevation taken on the line AA of FIG. 1;

FIG. 2A is an enlarged sectional elevational view of a modified construction employing an apertured annular plate; and,

FIG. 3 is a sectional elevation taken on the line 8-8 of FIG. 1.

Referring to the drawings, the apparatus comprises basically a casing 10 having a tachometer mounting l2 and there is a handwheel 14 which is a speed adjuster as will be explained hereinafter.

Inside the casing 10 there is a mixing bowl I6 of inverted frusto-conical form having a base plate 18 and the top of which is covered by a cover assembly comprising a filter ring 20 and a removable discharge plate 22. Within the mixing bowl 16 is a mixing member 24 of conventional form which is carried at the lower end of a support sleeve 26, the top end of which is connected to a central shaft 28 which passes through the bowl and the bottom of the casing. At the bottom end of the shaft there is provided a drive means pulley 30 by which the shaft can be rotated by drive means and as will be explained later. The shaft 28 is carried in bearings 32 and 34 and under the bowl the shaft is located in a rotatable sleeve 36 mounted on an internal frame of the casing on bearings 38.

The sleeve 36 is firmly secured to the base I8 of the bowl l6 and a one-way clutch device 40 is connected between the sleeve 36 and the shaft 28, the arrange ment being that in one direction of rotation of shaft 28 there is no drive to the sleeve 36 on the bowl 16 but when the shaft is rotated in the opposite direction the one-way clutch engages and drive is transmitted to the sleeve 36 and bowl l6 and these components rotate in unison with the shaft 28 and its mixing member 24.

Extending upwardly from base 18 of bowl 16 is a sealing sleeve 42 which lies between the shaft 28 and the supporting sleeve 26 and extends to the top of shaft 28 in order to effect a sealing of the interior of the bowl 16 from the clutch 40.

FIG. 3 shows clearly the positioning of the prime mover for the apparatus, this prime mover being in the form of an electric motor 42. The drive shaft of the motor is connected to the control pulley 44 of an infinitely variable ratio belt and pulley transmission of which the follower pulley, being shown at 46 is firmly secured to an intermediate shaft 48 at the end of which there is a pulley block 50 and the belts trained round pulley block 50 are also trained round the pulley block 30 described with reference to and illustrated in FIG. 2. From the auxiliary shaft 48 there is taken a flexible cable drive 52 to the tachometer 54 carried by the tachometer mounting 12.

Also shown in FIG. 3, the handwheel 14 is connected by shaft to an adjusting mechanism 56 of conventional design for adjusting the effective diameter of pulley 44 to vary, again in conventional manner, the speed ratio between the motor 42 and the auxiliary shaft 48.

The operation of the apparatus is very simple insofar as the material to be milled is charged with the milling elements into the bowl l6 and in the initial operation the motor is driven to cause shaft 28 to rotate in a direction in which bowl 16 is stationary. The bowl may be held in a stationary position by the engagement of friction pads on a brake disc 58 as shown in FIG. 2. At the end of the milling operation, the drive direction of the motor is reversed causing the bowl and mixing member to rotate together and this causes the material and the milling elements by centrifugal action to ride up the inner wall of the bowl to the screen ring 20 whereat the milled material is filtered from the milling elements and is collected in a collection trough 60 at the top of the casing.

in the milling operation, the material being milled tends to heat up and it is expedient to arrange for the heat to be removed either during or after the milling operation.

To this end, the bowl I6 is provided with a cooling jacket as defined by a first plate 62 which is curved to the countour of the outside of the bowl 16 so as to define a first cavity 64 extending approximately for half the height of the bowl and there is a second plate 66 which surrounds the plate and is spaced therefrom so as to define a second annular cavity 68 surrounding the first cavity, the two cavities being freely in communication at the bottom ends thereof. The top end of the first cavity 64 is located considerably above that of the second cavity 68 and the top end of the first cavity is left open and, indeed, the top edge of plate 62 is as shown flared outwardly. The top end of the second cavity 68, as shown in FIG. 2A, may be restricted in the extent to which it is open although, as will be explained hereinafter, it must be open to such an extent to allow the flow of cooling liquid out of the top of this cavity.

A cooling liquid feed ring 70 is firmly connected to the inside of the casing and is located slightly above the top end of cavity 64. This ring is circular so as to follow the top end of cavity 64 and is provided with a plurality of apertures whereby cooling fluid may be jetted from the ring which is referenced 70 in the drawings into the top end of cavity 64. The ring will of course be connected to a source of cooling fluid, such as water. The cooling fluid can of course be supplied to the top end of cavity 64 during operation of the equipment.

Cooling fluid which is delivered to cavity 64 flows down cavity 64 and up cavity 68 and eventually out of and over the top edge of the second plate 66 into a space from which it is easily collected.

The creation of a restriction to the flow of the liquid at the top end of cavity 68 by means of an apertured plate 68A as shown in FIG. 2A enables the creation of a surplus head in cavity 64 whereby the cooling liquid will be retained in the cavity 64 longer than it would be if the top end of cavity 68 were simply open.

The advantage of this particular cooling arrangement is that no complicated feed passages are necessary and furthermore no difficult sealing problems arise in connection with the creation of the cooling jacket such as arise when efforts are made to lead the cooling fluid from under the bowl and up through passages created in the bowl and the mounting shafts and sleeve.

In order to discharge the cooling fluid from the cavity 64 and 68 at the end of a milling operation it is simply a matter of spinning the bowl and the centrifugal action forces the liquid in cavities 64 and 68 up and out of these cavities.

In the example of the invention, the plates 62 and 66 will be of suitable heat conductive metal.

I claim:

1. A milling machine comprising a bowl having an external cooling jacket into which water may be introduced to cool the bowl, said jacket being defined by a first plate extending around the bowl so as to provide a first cavity between the bowl and first plate, and a second plate extending around the first plate so as to provide a second cavity between the first and second plates, said first and second cavities being in communication at the lower ends thereof, and the top of the first cavity being open and the top of the second cavity being located so that cooling fluid introduced into the first cavity through the open top thereof flows down the first cavity then up the second cavity and then over and outwardly of the top edge of the second cavity.

2. A milling machine according to claim 1, wherein the said first and second plates extend around the whole periphery of the bowl.

3. A milling machine according to claim I, wherein the top edge of the first plate is located above the top edge of the second plate.

4. A milling machine according to claim 1, including a stationary water supply pipe located adjacent the top edge of the upper cavity and having holes therein from which water can issue in jets directed to the open top of the first cavity.

5. A milling machine according to claim 1, wherein there is a restricting means at the top end of the second cavity for restricting the cooling fluid in order to enable the build up ofa head of cooling fluid in the first cavity.

6. A milling machine according to claim 5, wherein said restricting means is an apertured plate closing the top of the second cavity.

7. A milling machine according to claim 1, wherein the bowl is of circular sections and said first and second plates are curved to follow the bowl shape. 

1. A milling machine comprising a bowl having an external cooling jacket into which water may be introduced to cool the bowl, said jacket being defined by a first plate extending around the bowl so as to provide a first cavity between the bowl and first plate, and a second plate extending around the first plate so as to provide a second cavity between the first and second plates, said first and second cavities being in communication at the lower ends thereof, and the top of the first cavity being open and the top of the second cavity being located so that cooling fluid introduced into the first cavity through the open top thereof flows down the first cavity then up the second cavity and then over and outwardly of the top edge of the second cavity.
 2. A milling machine according to claim 1, wherein the said first and second plates extend around the whole periphery of the bowl.
 3. A milling machine according to claim 1, wherein the top edge of the first plate is located above the top edge of the second plate.
 4. A milling machine according to claim 1, incLuding a stationary water supply pipe located adjacent the top edge of the upper cavity and having holes therein from which water can issue in jets directed to the open top of the first cavity.
 5. A milling machine according to claim 1, wherein there is a restricting means at the top end of the second cavity for restricting the cooling fluid in order to enable the build up of a head of cooling fluid in the first cavity.
 6. A milling machine according to claim 5, wherein said restricting means is an apertured plate closing the top of the second cavity.
 7. A milling machine according to claim 1, wherein the bowl is of circular sections and said first and second plates are curved to follow the bowl shape. 